Performed fall maintenance on a 2015 York gas furnace. Customer reports no issues with heating so far. Filter was recently changed. Sensors and switches wer cleaned and tested. Gas valve and ignitor were tested and recorded. Heating temperature rise is in range. Primary blower and inducer motor are clean of oil and amping in range. Visual burn marks are present on the control board, this is concerning for the reliability and longevity of the entire system including AC. For this reason I am recommending a voltage regulator and equipment protection. Customer was briefed of the potential issues. System was cycled and running at end of appointment.